3.3TT Max tire diameter difference (front to rear) before triggering the AWD warning light?

[ElChanclo]

I was test fitting some larger wheels last year (27.7" OD fronts with the OEM 26.0" rears), but during the test drive I got an AWD warning light on the dash after a few minutes. Once I threw on the larger rears to match, the light went off.

Now I'm trying to mix & match some staggered tire & rim combos and wondering what I can get away with before upsetting the dash lights.

Anyone with an AWD Stinger successfully running different diameter tires front to rear?

 

[Ohiocruiser]

It's a horrible idea to run different diameter tires on awd. You will break differential or transfer case or transmission pretty quickly. You can run different width tires. Or even different diameter rims ( will look, and probably drive pretty bad though). But you have to make sure tires are the same diameter.

 

[Snowwhite]

Stock staggered tires are 5mm or 0.4% off In circumference. I wouldn’t go any further off than that.

 

[Snicklefritz]

Now I'm trying to mix & match some staggered tire & rim combos and wondering what I can get away with before upsetting the dash lights.

After all the discussions on here over the years about the importance of keeping AWD front and rear OD the same, Ima surprised to read this question. What @Ohiocruiser said.

 

[ElChanclo]

After all the discussions on here over the years about the importance of keeping AWD front and rear OD the same, Ima surprised to read this question. What @Ohiocruiser said.

The stock wheels aren't identical so there's obviously some leeway built in, just want to know what the safe limit is. If you have a link please share.

It looks like the more the difference in circumference the harder the AWD system has to strain to keep up. It's talked me off the ledge at least, not worth straining the drive train to find out.

Some AWD systems can't even handle a singe tire being replaced with full tread without getting in trouble.

The best reference I could find:

Audi	As published in their vehicle owner's manual, "rolling radius of all 4 tires must remain the same" or within 4/32-inch of each other in remaining tread depth.
Porsche	Cayenne within 30% of the other tire on the same axle's remaining treadwear.
Nissan	GT-R when replacing less than four (4) tires, each tire continuing in service must have at least 6/32 inch (5 mm) of remaining tread depth.
Subaru	Within 1/4-inch of tire circumference or about 2/32-inch of each other in remaining tread depth.

 

[D.J.]

It would only be hard on the transfer case clutch pack.

Don't do it.

 

[Snicklefritz]

The stock wheels aren't identical so there's obviously some leeway built in, just want to know what the safe limit is. If you have a link please share.

Well, just use "FIND". Here's a search result I turned up. That could keep you busy reading for a spell. Search results for query: outside diameter od difference awd

 

[Kodiack]

The stock factory tires are staggered but maintain the same outside diameter.
You can go with a square set maintaining that same outer diameter...thats what I run for winters.

 

[ElChanclo]

For science and future reference I threw on the stock 26.0" rear wheels (255/35r19) while I had the 25.1" wheels up front (225/40r18) to see if the 0.9" diameter delta would trigger the AWD dashboard warning light. Both sets had ~50% remaining tread. FYI the setup that triggered the light had the 27.7" fronts (225/55r18) with the OEM 26.0" rears (255/35r19), so a 1.7" delta.

I drove about 25km rural and highway with no warnings or dashboard lights coming up this time.
NOTE: This could be because the flagged setup had the larger wheels at the front, where this test had the larger wheels at the rear.

That settles my curiosity for now, and even though the dashboard didn't complain about a 0.9" wheel diameter difference front to rear, after all my reading on the subject I would seriously avoid any variation in diameter where possible, as it leads to ever greater stress and wear on the system, and possibly mechanical failure.

 

[SRV]

A perfect match would be:

255/35/19
295/30/19

However, they are NOT available for all-seasons.

For all-seasons, I had to go with:

245/35/19
285/30/19

A year and a half ago, I went thru all of this - I wasn't aware at the time that the front/rear tire diameters need to match as close as possible for AWD.

 

[StingerMG]

A perfect match would be:

255/35/19
295/30/19

However, they are NOT available for all-seasons.

For all-seasons, I had to go with:

245/35/19
285/30/19

A year and a half ago, I went thru all of this - I wasn't aware at the time that the front/rear tire diameters need to match as close as possible for AWD.

Nice setup, even though I'm RWD I don't see in many people running 245/35 and 285/30. I use 245/35/20 and 285/30/20 and have Falken FK460 all season tires.

 

[ElChanclo]

NOTE: This could be because the flagged setup had the larger wheels at the front, where this test had the larger wheels at the rear.

I just threw the 26.0" OEM fronts on, with the 27.7" winter rears (so smaller wheels front, larger wheels rear) and it flagged the AWD light within half a block. Just posting for future reference.

FRONT + REAR:

27.7" + 26.0" (1.7" OD delta)= AWD FAULT

26.0" + 27.7" (1.7" OD delta)= AWD FAULT

25.1" + 26.0" (0.9" OD delta)= No Faults

OEM 26.0" (225/40r19 front, 255/35r19 rear)
SNOW 27.7" (225/55r18)
ALLS 25.1" (225/40r18)

 

[7Andrei7]

Even on RWD stingers, having 0.6" smaller OD rear wheels (compared to fronts) will trigger the TC under certain conditions.
Definitely DON'T use different OD tires on an AWD car.

 

[ElChanclo]

Even on RWD stingers, having 0.6" smaller OD rear wheels (compared to fronts) will trigger the TC under certain conditions.
Definitely DON'T use different OD tires on an AWD car.

Interesting, so 0.6" OD difference will trigger the TC but not show any errors on the dash?
Even the OEM tires are off by 3mm, so there's clearly a margin for error before you experience issues.

 

[D.J.]

Interesting, so 0.6" OD difference will trigger the TC but not show any errors on the dash?
Even the OEM tires are off by 3mm, so there's clearly a margin for error before you experience issues.

3mm is MUCH less than 0.6"
3mm = 0.1181"

The percentage difference between 0.118" and 0.6" is 80.33%.


I have run various brands, mixed front and rear - but never measured actual circumference of any.

 

[Snicklefritz]

Interesting, so 0.6" OD difference will trigger the TC but not show any errors on the dash?

Andrei's Stinger is RWD, so, it would not throw an AWD error.